Riley told his mom that multiplying whole numbers by multiples of 10 was easy because you just count zeros in the factors and put them in the product...

Question

7,000 x 600 = 4,200,000
Riley's mom said this strategy will not always works? Why not? Give example

Answer 1

You have to watch out for extra factors of 10, which add zeroes to the product.

40 x 50 ≠ 200

Answer 2

Problem with your example is that the product of 4x5 is 20 then you would add the two zeros to complete the strategy giving the proper answer of 2000.

Answer 3

Because you have to watch out for extra factors of 10, which add zeros to the product.

40x50=200

Answer 4

you have to remember, the factors of 10 that add zero the product. ex. 50 x 80 = 4,000

Answer 5

but if you are counting the zeros and adding it to the numbers in front that have already been multiplied, then he is correct you dont have to remember anything other than multiply anything thats not a zero and then add the zeros to it. so it will always work

Answer 6

I dont get this because i have this on my homework but my teacher said that there was an answer