1、24.6-3.98+5.4-6.02
24.6-3.98+5.4-6.02
=(24.6+5.4)-(3.98+6.02)
=30- 10
=20
2、27× 17/26
27× 17/26
=(26+ 1)× 17/26
=26× 17/26+ 1× 17/26
= 17+ 17/26
= 17 and 17/26
3、528-99
528-99
=528-( 100- 1)
=528- 100+ 1
=428+ 1
=429
4、 1.2×2.5+0.8×2.5
1.2×2.5+0.8×2.5
=( 1.2+0.8)×2.5
=2×2.5
=5?
5、2.96×40
2.96×40
=29.6x4
=(30-0.4)x4
=30×4+0.4×4
= 120- 1.6
= 1 18.4