Question

When we mentally multiply 15 by 10 we can simply attach 0 to 15 to make the product 150 when we multiply 1.5 by 10 why can't we attach zero to make the product 1.50

Answer 1

No, since we have a decimal point we have to move the decimal point one digit towards the right when multiplied with 10. And one digit towards the left when divided by ten

And now since we must multiply with 10 the decimal point must move one digit towards the left so the answer is 15