Question

tính nhanh

15.20-15.10+15.40

12.10+24.15+24

30.15+450.12

Answer 1

a, =15.(20-10+40)=750

b,=12.(10+30+2)=504

c, =30.(15+180)=5850

Answer 2

15.20-15.10+15.40

=15.(20-10+40)

=15.50

=750

12.10+24.15+24

=12.(2.5)+24.15+24.1

=(12.2).5+24.15+24.1

=24.5+24.15+24.1

=24.(5+15+1)

=24.21

=504

30.15+450.12

=450+450.12

=450.1+450.12

=450.(1+12)

=450.13

=5850

Answer 3

Ta có :

15.20-15.10+15.40

=15.(20-10+40)

=15.50

=750

12.10+24.15+24

=12.(2.5)+24.15+24.1

=(12.2).5+24.15+24.1

=24.5+24.15+24.1

=24.(5+15+1)

=24.21

=504

30.15+450.12

=450+450.12

=450.1+450.12

=450.(1+12)

=450.13

=5850