Tính nhanh:
a, 25.204
b, 43.17 + 29.57 + 13.43 + 57
c, 3.2.5.8 + 4.37.6 + 2.38.12
Tính nhanh: a, 25.204 b, 43.17 + 29.57 + 13.43 + 57 c, 3.2.5.8 + 4.37.6 + 2.38.12
By Eden
By Eden
Tính nhanh:
a, 25.204
b, 43.17 + 29.57 + 13.43 + 57
c, 3.2.5.8 + 4.37.6 + 2.38.12
Giải thích các bước giải:
a, 25.204=25.(200+4)
=25.200+25.4
=5000+100=5100
b, 43.17 + 29.57 + 13.43 + 57
=43.17 + 29.57 + 13.43 + 57.1
=43.(17+13)+57.(29+1)
=43.30+57.30
=30.(43+57)
=30.100=30000
c, 3.2.5.8 + 4.37.6 + 2.38.12
=(3.8).(2.5)+(4.6).37+(2.12).38
=24.10+24.37+24.38
=24.(10+37+38)
=24.85=2040
`a,25.204=25(200+4)=25.200+25.4=5000+100=5100`
`b,43.17+29.57+13.43+57=(43.17+13.43)+(29.57+57)`
` =43(17+13)+57(29+1)`
` =43.30+57.30`
` =30(43+57)=30.100=3000`
`c,3.25.8+4.37.6+2.38.12=24.25+24.37+24.38`
`=24(25+37+38)`
` =24.100=2400`