Question

Sue wants to use mental math to find 7 x 53. Write an expression she could use.

Answer 1

7 x 50 rounding the second digit to the nearest 10 and then multiply 7 x 3 and add the two answers together 350 + 21 = 371

Answer 2

When we want solve expression mentally, that is, without writing down anything, a nice way is to separate number in simpler expressions, like tens for example.

So, in first place we could multiply 7 x 50, which involves a number expressed in tens, this product would be 350, then we multiply 7 x 3, which is 21, at the end, we sum both results 350 + 21 = 371. Therefore, the product is 371.

If we want to write an expression, it would be

7 x 50 + 7 x 3 = 350 + 21 = 371