Question

用递等式计算（能巧算的要巧算） 小学3年级的。

346+128+254 599-133-248
345+234+245 8X3-3X2 187-65-87 108-7X4

Answer 1

346+128+254
=(346+254)+128
=600+128
=728
599-133-248
=599-(133+248)
=599-381
=218
345+234+245
=345+245+234
=690+234
=924
8X3-3X2
=3×（8-2）
=3×6
=18
187-65-87
=187-87-65
=100-65
=35
108-7X4
=27×4-7×4
=4×（27-7）
=4×20
=80

Answer 2

346+128+254
＝346+254+128
＝600+128
＝728

599-133-248
＝599－（133+248）
＝599－381
＝218

345+234+245
＝345+245+234
＝590+234
＝590+10+224
＝600+224
＝824

8X3-3X2
＝（8－2）×3
＝6×3
＝18

187-65-87
＝187－87－65
＝100－65
＝35

108-7X4
＝108－28
＝108－8－20
＝100－20
＝80

Answer 3

346+128+254=346+254+128=600+128=728;
599-133-248=599-(133+248)=599-381=218;
345+234+245=345+245+234=590+234=600+234-10=834-10=824;
8x3-3x2=(8-2)x3=6x3=18;
187-65-87=187-87-65=100-65=35;
108-7x4=27x4-7x4=(27-7)x4=20x4=80.

Answer 4

728 218
824 18 35 80