IPv4 Subnet Calculator

Enter an IP with a CIDR prefix or a subnet mask to see its network, broadcast, host range, and host count. You can also split the network into smaller subnets.

Try:192.168.1.10/24 10.0.0.0/8 172.16.5.4/20 203.0.113.9/29

IPv6 calculator →

private IP (RFC 1918)10.2.16.0/21

network10.2.16.0/21

broadcast10.2.23.255

first host10.2.16.1

last host10.2.23.254

subnet mask255.255.248.0

wildcard0.0.7.255

addresses2,048

usable hosts2,046

classA

ipcalc 10.2.16.0/21

address00001010.00000010.00010000.00000000

subnet mask11111111.11111111.11111000.00000000

network00001010.00000010.00010000.00000000

broadcast00001010.00000010.00010111.11111111

green = network part, grey = host part

hex0x0a021000

decimal167907328

reverse dns0.16.2.10.in-addr.arpa

ipv4-mapped::ffff:a02:1000

/21 split into /32 · 2,048 subnets

close ×

#	network	host range	broadcast
1	10.2.16.0/32	10.2.16.0 – 10.2.16.0	10.2.16.0
2	10.2.16.1/32	10.2.16.1 – 10.2.16.1	10.2.16.1
3	10.2.16.2/32	10.2.16.2 – 10.2.16.2	10.2.16.2
4	10.2.16.3/32	10.2.16.3 – 10.2.16.3	10.2.16.3
5	10.2.16.4/32	10.2.16.4 – 10.2.16.4	10.2.16.4
6	10.2.16.5/32	10.2.16.5 – 10.2.16.5	10.2.16.5
7	10.2.16.6/32	10.2.16.6 – 10.2.16.6	10.2.16.6
8	10.2.16.7/32	10.2.16.7 – 10.2.16.7	10.2.16.7
9	10.2.16.8/32	10.2.16.8 – 10.2.16.8	10.2.16.8
10	10.2.16.9/32	10.2.16.9 – 10.2.16.9	10.2.16.9
11	10.2.16.10/32	10.2.16.10 – 10.2.16.10	10.2.16.10
12	10.2.16.11/32	10.2.16.11 – 10.2.16.11	10.2.16.11
13	10.2.16.12/32	10.2.16.12 – 10.2.16.12	10.2.16.12
14	10.2.16.13/32	10.2.16.13 – 10.2.16.13	10.2.16.13
15	10.2.16.14/32	10.2.16.14 – 10.2.16.14	10.2.16.14
16	10.2.16.15/32	10.2.16.15 – 10.2.16.15	10.2.16.15
17	10.2.16.16/32	10.2.16.16 – 10.2.16.16	10.2.16.16
18	10.2.16.17/32	10.2.16.17 – 10.2.16.17	10.2.16.17
19	10.2.16.18/32	10.2.16.18 – 10.2.16.18	10.2.16.18
20	10.2.16.19/32	10.2.16.19 – 10.2.16.19	10.2.16.19
21	10.2.16.20/32	10.2.16.20 – 10.2.16.20	10.2.16.20
22	10.2.16.21/32	10.2.16.21 – 10.2.16.21	10.2.16.21
23	10.2.16.22/32	10.2.16.22 – 10.2.16.22	10.2.16.22
24	10.2.16.23/32	10.2.16.23 – 10.2.16.23	10.2.16.23
25	10.2.16.24/32	10.2.16.24 – 10.2.16.24	10.2.16.24
26	10.2.16.25/32	10.2.16.25 – 10.2.16.25	10.2.16.25
27	10.2.16.26/32	10.2.16.26 – 10.2.16.26	10.2.16.26
28	10.2.16.27/32	10.2.16.27 – 10.2.16.27	10.2.16.27
29	10.2.16.28/32	10.2.16.28 – 10.2.16.28	10.2.16.28
30	10.2.16.29/32	10.2.16.29 – 10.2.16.29	10.2.16.29
31	10.2.16.30/32	10.2.16.30 – 10.2.16.30	10.2.16.30
32	10.2.16.31/32	10.2.16.31 – 10.2.16.31	10.2.16.31
33	10.2.16.32/32	10.2.16.32 – 10.2.16.32	10.2.16.32
34	10.2.16.33/32	10.2.16.33 – 10.2.16.33	10.2.16.33
35	10.2.16.34/32	10.2.16.34 – 10.2.16.34	10.2.16.34
36	10.2.16.35/32	10.2.16.35 – 10.2.16.35	10.2.16.35
37	10.2.16.36/32	10.2.16.36 – 10.2.16.36	10.2.16.36
38	10.2.16.37/32	10.2.16.37 – 10.2.16.37	10.2.16.37
39	10.2.16.38/32	10.2.16.38 – 10.2.16.38	10.2.16.38
40	10.2.16.39/32	10.2.16.39 – 10.2.16.39	10.2.16.39
41	10.2.16.40/32	10.2.16.40 – 10.2.16.40	10.2.16.40
42	10.2.16.41/32	10.2.16.41 – 10.2.16.41	10.2.16.41
43	10.2.16.42/32	10.2.16.42 – 10.2.16.42	10.2.16.42
44	10.2.16.43/32	10.2.16.43 – 10.2.16.43	10.2.16.43
45	10.2.16.44/32	10.2.16.44 – 10.2.16.44	10.2.16.44
46	10.2.16.45/32	10.2.16.45 – 10.2.16.45	10.2.16.45
47	10.2.16.46/32	10.2.16.46 – 10.2.16.46	10.2.16.46
48	10.2.16.47/32	10.2.16.47 – 10.2.16.47	10.2.16.47
49	10.2.16.48/32	10.2.16.48 – 10.2.16.48	10.2.16.48
50	10.2.16.49/32	10.2.16.49 – 10.2.16.49	10.2.16.49
51	10.2.16.50/32	10.2.16.50 – 10.2.16.50	10.2.16.50
52	10.2.16.51/32	10.2.16.51 – 10.2.16.51	10.2.16.51
53	10.2.16.52/32	10.2.16.52 – 10.2.16.52	10.2.16.52
54	10.2.16.53/32	10.2.16.53 – 10.2.16.53	10.2.16.53
55	10.2.16.54/32	10.2.16.54 – 10.2.16.54	10.2.16.54
56	10.2.16.55/32	10.2.16.55 – 10.2.16.55	10.2.16.55
57	10.2.16.56/32	10.2.16.56 – 10.2.16.56	10.2.16.56
58	10.2.16.57/32	10.2.16.57 – 10.2.16.57	10.2.16.57
59	10.2.16.58/32	10.2.16.58 – 10.2.16.58	10.2.16.58
60	10.2.16.59/32	10.2.16.59 – 10.2.16.59	10.2.16.59
61	10.2.16.60/32	10.2.16.60 – 10.2.16.60	10.2.16.60
62	10.2.16.61/32	10.2.16.61 – 10.2.16.61	10.2.16.61
63	10.2.16.62/32	10.2.16.62 – 10.2.16.62	10.2.16.62
64	10.2.16.63/32	10.2.16.63 – 10.2.16.63	10.2.16.63
65	10.2.16.64/32	10.2.16.64 – 10.2.16.64	10.2.16.64
66	10.2.16.65/32	10.2.16.65 – 10.2.16.65	10.2.16.65
67	10.2.16.66/32	10.2.16.66 – 10.2.16.66	10.2.16.66
68	10.2.16.67/32	10.2.16.67 – 10.2.16.67	10.2.16.67
69	10.2.16.68/32	10.2.16.68 – 10.2.16.68	10.2.16.68
70	10.2.16.69/32	10.2.16.69 – 10.2.16.69	10.2.16.69
71	10.2.16.70/32	10.2.16.70 – 10.2.16.70	10.2.16.70
72	10.2.16.71/32	10.2.16.71 – 10.2.16.71	10.2.16.71
73	10.2.16.72/32	10.2.16.72 – 10.2.16.72	10.2.16.72
74	10.2.16.73/32	10.2.16.73 – 10.2.16.73	10.2.16.73
75	10.2.16.74/32	10.2.16.74 – 10.2.16.74	10.2.16.74
76	10.2.16.75/32	10.2.16.75 – 10.2.16.75	10.2.16.75
77	10.2.16.76/32	10.2.16.76 – 10.2.16.76	10.2.16.76
78	10.2.16.77/32	10.2.16.77 – 10.2.16.77	10.2.16.77
79	10.2.16.78/32	10.2.16.78 – 10.2.16.78	10.2.16.78
80	10.2.16.79/32	10.2.16.79 – 10.2.16.79	10.2.16.79
81	10.2.16.80/32	10.2.16.80 – 10.2.16.80	10.2.16.80
82	10.2.16.81/32	10.2.16.81 – 10.2.16.81	10.2.16.81
83	10.2.16.82/32	10.2.16.82 – 10.2.16.82	10.2.16.82
84	10.2.16.83/32	10.2.16.83 – 10.2.16.83	10.2.16.83
85	10.2.16.84/32	10.2.16.84 – 10.2.16.84	10.2.16.84
86	10.2.16.85/32	10.2.16.85 – 10.2.16.85	10.2.16.85
87	10.2.16.86/32	10.2.16.86 – 10.2.16.86	10.2.16.86
88	10.2.16.87/32	10.2.16.87 – 10.2.16.87	10.2.16.87
89	10.2.16.88/32	10.2.16.88 – 10.2.16.88	10.2.16.88
90	10.2.16.89/32	10.2.16.89 – 10.2.16.89	10.2.16.89
91	10.2.16.90/32	10.2.16.90 – 10.2.16.90	10.2.16.90
92	10.2.16.91/32	10.2.16.91 – 10.2.16.91	10.2.16.91
93	10.2.16.92/32	10.2.16.92 – 10.2.16.92	10.2.16.92
94	10.2.16.93/32	10.2.16.93 – 10.2.16.93	10.2.16.93
95	10.2.16.94/32	10.2.16.94 – 10.2.16.94	10.2.16.94
96	10.2.16.95/32	10.2.16.95 – 10.2.16.95	10.2.16.95
97	10.2.16.96/32	10.2.16.96 – 10.2.16.96	10.2.16.96
98	10.2.16.97/32	10.2.16.97 – 10.2.16.97	10.2.16.97
99	10.2.16.98/32	10.2.16.98 – 10.2.16.98	10.2.16.98
100	10.2.16.99/32	10.2.16.99 – 10.2.16.99	10.2.16.99
101	10.2.16.100/32	10.2.16.100 – 10.2.16.100	10.2.16.100
102	10.2.16.101/32	10.2.16.101 – 10.2.16.101	10.2.16.101
103	10.2.16.102/32	10.2.16.102 – 10.2.16.102	10.2.16.102
104	10.2.16.103/32	10.2.16.103 – 10.2.16.103	10.2.16.103
105	10.2.16.104/32	10.2.16.104 – 10.2.16.104	10.2.16.104
106	10.2.16.105/32	10.2.16.105 – 10.2.16.105	10.2.16.105
107	10.2.16.106/32	10.2.16.106 – 10.2.16.106	10.2.16.106
108	10.2.16.107/32	10.2.16.107 – 10.2.16.107	10.2.16.107
109	10.2.16.108/32	10.2.16.108 – 10.2.16.108	10.2.16.108
110	10.2.16.109/32	10.2.16.109 – 10.2.16.109	10.2.16.109
111	10.2.16.110/32	10.2.16.110 – 10.2.16.110	10.2.16.110
112	10.2.16.111/32	10.2.16.111 – 10.2.16.111	10.2.16.111
113	10.2.16.112/32	10.2.16.112 – 10.2.16.112	10.2.16.112
114	10.2.16.113/32	10.2.16.113 – 10.2.16.113	10.2.16.113
115	10.2.16.114/32	10.2.16.114 – 10.2.16.114	10.2.16.114
116	10.2.16.115/32	10.2.16.115 – 10.2.16.115	10.2.16.115
117	10.2.16.116/32	10.2.16.116 – 10.2.16.116	10.2.16.116
118	10.2.16.117/32	10.2.16.117 – 10.2.16.117	10.2.16.117
119	10.2.16.118/32	10.2.16.118 – 10.2.16.118	10.2.16.118
120	10.2.16.119/32	10.2.16.119 – 10.2.16.119	10.2.16.119
121	10.2.16.120/32	10.2.16.120 – 10.2.16.120	10.2.16.120
122	10.2.16.121/32	10.2.16.121 – 10.2.16.121	10.2.16.121
123	10.2.16.122/32	10.2.16.122 – 10.2.16.122	10.2.16.122
124	10.2.16.123/32	10.2.16.123 – 10.2.16.123	10.2.16.123
125	10.2.16.124/32	10.2.16.124 – 10.2.16.124	10.2.16.124
126	10.2.16.125/32	10.2.16.125 – 10.2.16.125	10.2.16.125
127	10.2.16.126/32	10.2.16.126 – 10.2.16.126	10.2.16.126
128	10.2.16.127/32	10.2.16.127 – 10.2.16.127	10.2.16.127
129	10.2.16.128/32	10.2.16.128 – 10.2.16.128	10.2.16.128
130	10.2.16.129/32	10.2.16.129 – 10.2.16.129	10.2.16.129
131	10.2.16.130/32	10.2.16.130 – 10.2.16.130	10.2.16.130
132	10.2.16.131/32	10.2.16.131 – 10.2.16.131	10.2.16.131
133	10.2.16.132/32	10.2.16.132 – 10.2.16.132	10.2.16.132
134	10.2.16.133/32	10.2.16.133 – 10.2.16.133	10.2.16.133
135	10.2.16.134/32	10.2.16.134 – 10.2.16.134	10.2.16.134
136	10.2.16.135/32	10.2.16.135 – 10.2.16.135	10.2.16.135
137	10.2.16.136/32	10.2.16.136 – 10.2.16.136	10.2.16.136
138	10.2.16.137/32	10.2.16.137 – 10.2.16.137	10.2.16.137
139	10.2.16.138/32	10.2.16.138 – 10.2.16.138	10.2.16.138
140	10.2.16.139/32	10.2.16.139 – 10.2.16.139	10.2.16.139
141	10.2.16.140/32	10.2.16.140 – 10.2.16.140	10.2.16.140
142	10.2.16.141/32	10.2.16.141 – 10.2.16.141	10.2.16.141
143	10.2.16.142/32	10.2.16.142 – 10.2.16.142	10.2.16.142
144	10.2.16.143/32	10.2.16.143 – 10.2.16.143	10.2.16.143
145	10.2.16.144/32	10.2.16.144 – 10.2.16.144	10.2.16.144
146	10.2.16.145/32	10.2.16.145 – 10.2.16.145	10.2.16.145
147	10.2.16.146/32	10.2.16.146 – 10.2.16.146	10.2.16.146
148	10.2.16.147/32	10.2.16.147 – 10.2.16.147	10.2.16.147
149	10.2.16.148/32	10.2.16.148 – 10.2.16.148	10.2.16.148
150	10.2.16.149/32	10.2.16.149 – 10.2.16.149	10.2.16.149
151	10.2.16.150/32	10.2.16.150 – 10.2.16.150	10.2.16.150
152	10.2.16.151/32	10.2.16.151 – 10.2.16.151	10.2.16.151
153	10.2.16.152/32	10.2.16.152 – 10.2.16.152	10.2.16.152
154	10.2.16.153/32	10.2.16.153 – 10.2.16.153	10.2.16.153
155	10.2.16.154/32	10.2.16.154 – 10.2.16.154	10.2.16.154
156	10.2.16.155/32	10.2.16.155 – 10.2.16.155	10.2.16.155
157	10.2.16.156/32	10.2.16.156 – 10.2.16.156	10.2.16.156
158	10.2.16.157/32	10.2.16.157 – 10.2.16.157	10.2.16.157
159	10.2.16.158/32	10.2.16.158 – 10.2.16.158	10.2.16.158
160	10.2.16.159/32	10.2.16.159 – 10.2.16.159	10.2.16.159
161	10.2.16.160/32	10.2.16.160 – 10.2.16.160	10.2.16.160
162	10.2.16.161/32	10.2.16.161 – 10.2.16.161	10.2.16.161
163	10.2.16.162/32	10.2.16.162 – 10.2.16.162	10.2.16.162
164	10.2.16.163/32	10.2.16.163 – 10.2.16.163	10.2.16.163
165	10.2.16.164/32	10.2.16.164 – 10.2.16.164	10.2.16.164
166	10.2.16.165/32	10.2.16.165 – 10.2.16.165	10.2.16.165
167	10.2.16.166/32	10.2.16.166 – 10.2.16.166	10.2.16.166
168	10.2.16.167/32	10.2.16.167 – 10.2.16.167	10.2.16.167
169	10.2.16.168/32	10.2.16.168 – 10.2.16.168	10.2.16.168
170	10.2.16.169/32	10.2.16.169 – 10.2.16.169	10.2.16.169
171	10.2.16.170/32	10.2.16.170 – 10.2.16.170	10.2.16.170
172	10.2.16.171/32	10.2.16.171 – 10.2.16.171	10.2.16.171
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174	10.2.16.173/32	10.2.16.173 – 10.2.16.173	10.2.16.173
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177	10.2.16.176/32	10.2.16.176 – 10.2.16.176	10.2.16.176
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179	10.2.16.178/32	10.2.16.178 – 10.2.16.178	10.2.16.178
180	10.2.16.179/32	10.2.16.179 – 10.2.16.179	10.2.16.179
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208	10.2.16.207/32	10.2.16.207 – 10.2.16.207	10.2.16.207
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210	10.2.16.209/32	10.2.16.209 – 10.2.16.209	10.2.16.209
211	10.2.16.210/32	10.2.16.210 – 10.2.16.210	10.2.16.210
212	10.2.16.211/32	10.2.16.211 – 10.2.16.211	10.2.16.211
213	10.2.16.212/32	10.2.16.212 – 10.2.16.212	10.2.16.212
214	10.2.16.213/32	10.2.16.213 – 10.2.16.213	10.2.16.213
215	10.2.16.214/32	10.2.16.214 – 10.2.16.214	10.2.16.214
216	10.2.16.215/32	10.2.16.215 – 10.2.16.215	10.2.16.215
217	10.2.16.216/32	10.2.16.216 – 10.2.16.216	10.2.16.216
218	10.2.16.217/32	10.2.16.217 – 10.2.16.217	10.2.16.217
219	10.2.16.218/32	10.2.16.218 – 10.2.16.218	10.2.16.218
220	10.2.16.219/32	10.2.16.219 – 10.2.16.219	10.2.16.219
221	10.2.16.220/32	10.2.16.220 – 10.2.16.220	10.2.16.220
222	10.2.16.221/32	10.2.16.221 – 10.2.16.221	10.2.16.221
223	10.2.16.222/32	10.2.16.222 – 10.2.16.222	10.2.16.222
224	10.2.16.223/32	10.2.16.223 – 10.2.16.223	10.2.16.223
225	10.2.16.224/32	10.2.16.224 – 10.2.16.224	10.2.16.224
226	10.2.16.225/32	10.2.16.225 – 10.2.16.225	10.2.16.225
227	10.2.16.226/32	10.2.16.226 – 10.2.16.226	10.2.16.226
228	10.2.16.227/32	10.2.16.227 – 10.2.16.227	10.2.16.227
229	10.2.16.228/32	10.2.16.228 – 10.2.16.228	10.2.16.228
230	10.2.16.229/32	10.2.16.229 – 10.2.16.229	10.2.16.229
231	10.2.16.230/32	10.2.16.230 – 10.2.16.230	10.2.16.230
232	10.2.16.231/32	10.2.16.231 – 10.2.16.231	10.2.16.231
233	10.2.16.232/32	10.2.16.232 – 10.2.16.232	10.2.16.232
234	10.2.16.233/32	10.2.16.233 – 10.2.16.233	10.2.16.233
235	10.2.16.234/32	10.2.16.234 – 10.2.16.234	10.2.16.234
236	10.2.16.235/32	10.2.16.235 – 10.2.16.235	10.2.16.235
237	10.2.16.236/32	10.2.16.236 – 10.2.16.236	10.2.16.236
238	10.2.16.237/32	10.2.16.237 – 10.2.16.237	10.2.16.237
239	10.2.16.238/32	10.2.16.238 – 10.2.16.238	10.2.16.238
240	10.2.16.239/32	10.2.16.239 – 10.2.16.239	10.2.16.239
241	10.2.16.240/32	10.2.16.240 – 10.2.16.240	10.2.16.240
242	10.2.16.241/32	10.2.16.241 – 10.2.16.241	10.2.16.241
243	10.2.16.242/32	10.2.16.242 – 10.2.16.242	10.2.16.242
244	10.2.16.243/32	10.2.16.243 – 10.2.16.243	10.2.16.243
245	10.2.16.244/32	10.2.16.244 – 10.2.16.244	10.2.16.244
246	10.2.16.245/32	10.2.16.245 – 10.2.16.245	10.2.16.245
247	10.2.16.246/32	10.2.16.246 – 10.2.16.246	10.2.16.246
248	10.2.16.247/32	10.2.16.247 – 10.2.16.247	10.2.16.247
249	10.2.16.248/32	10.2.16.248 – 10.2.16.248	10.2.16.248
250	10.2.16.249/32	10.2.16.249 – 10.2.16.249	10.2.16.249
251	10.2.16.250/32	10.2.16.250 – 10.2.16.250	10.2.16.250
252	10.2.16.251/32	10.2.16.251 – 10.2.16.251	10.2.16.251
253	10.2.16.252/32	10.2.16.252 – 10.2.16.252	10.2.16.252
254	10.2.16.253/32	10.2.16.253 – 10.2.16.253	10.2.16.253
255	10.2.16.254/32	10.2.16.254 – 10.2.16.254	10.2.16.254
256	10.2.16.255/32	10.2.16.255 – 10.2.16.255	10.2.16.255

showing 256 of 2,048

01 / table

IPv4 CIDR prefix table.

Click a prefix longer than your network to split it into subnets.

prefix	subnet mask	addresses	hosts	in your /21
/0	0.0.0.0	4,294,967,296	4,294,967,294	-
/1	128.0.0.0	2,147,483,648	2,147,483,646	-
/2	192.0.0.0	1,073,741,824	1,073,741,822	-
/3	224.0.0.0	536,870,912	536,870,910	-
/4	240.0.0.0	268,435,456	268,435,454	-
/5	248.0.0.0	134,217,728	134,217,726	-
/6	252.0.0.0	67,108,864	67,108,862	-
/7	254.0.0.0	33,554,432	33,554,430	-
/8	255.0.0.0	16,777,216	16,777,214	-
/9	255.128.0.0	8,388,608	8,388,606	-
/10	255.192.0.0	4,194,304	4,194,302	-
/11	255.224.0.0	2,097,152	2,097,150	-
/12	255.240.0.0	1,048,576	1,048,574	-
/13	255.248.0.0	524,288	524,286	-
/14	255.252.0.0	262,144	262,142	-
/15	255.254.0.0	131,072	131,070	-
/16	255.255.0.0	65,536	65,534	-
/17	255.255.128.0	32,768	32,766	-
/18	255.255.192.0	16,384	16,382	-
/19	255.255.224.0	8,192	8,190	-
/20	255.255.240.0	4,096	4,094	-
/21	255.255.248.0	2,048	2,046	1
/22	255.255.252.0	1,024	1,022	2 split →
/23	255.255.254.0	512	510	4 split →
/24	255.255.255.0	256	254	8 split →
/25	255.255.255.128	128	126	16 split →
/26	255.255.255.192	64	62	32 split →
/27	255.255.255.224	32	30	64 split →
/28	255.255.255.240	16	14	128 split →
/29	255.255.255.248	8	6	256 split →
/30	255.255.255.252	4	2	512 split →
/31	255.255.255.254	2	2	1,024 split →
/32	255.255.255.255	1	1	2,048 split →

02 / faq

About this calculator.

How do I use this subnet calculator?

▼

Type an IP address followed by a prefix, like 192.168.1.10/24, or by a subnet mask, like 192.168.1.10 255.255.255.0. Without a prefix it uses /24. Click a row in the table to split the network into smaller subnets.

Why are usable hosts always 2 fewer?

▼

The first address in a subnet is the network address and the last is the broadcast address, so neither can go to a device. The exceptions are /31 (point-to-point links, RFC 3021) and /32 (a single address), which use every address.

Can I use it from a terminal?

▼

Yes. curl 'ipku.in/en/tools/ipv4-subnet-calculator?q=192.168.1.10/24' returns the result as plain text.

Learn how to work it out →