Question

Вычисли рационально
23+89+77
44+78+56
223+389+277
144+578+256
123+289+177
544+278+156

Answer 1

23+89+77=23+77+89=189
44+78+56=44+56+78=178
223+389+277=223+277+389=889
144+578+256=144+256+578=978
123+289+177=123+177+289=589
544+278+156=544+156+278=978

Answer 2

23+89+77 = (23+77)+89 = 100+89 = 189

44+78+56 = (44+56) + 78 = 100+78 = 178

223+398+277 = (223+277)+398 = 500+398 = 898

144+578+256 = (144+256) + 578 = 400+578=978

123+289+177 = (123+177)+289 = 300 + 289 = 589

544+278+156 = (544 + 156) + 278 = 700 + 278 = 978