Think of it as currency, for example
2 ones = 2 of $1 = $2 total tenths of dollar = 10 Cents then
20 x 10 Cents = 200 Cents = $2
so they are the same.
As is 200 hundredths, and so on
It's because a tenth means that you've divided it by 10. So if it's 20, it means you're multiplying tenths by 20, leaving you with 2 wholes.
For example, you have 2 cakes and you cut each into 10 slices, the slices are each one tenth of the whole cake, and in total there are 20 tenths.
Answer:
2 : 17
1 : 8.5
