Word problems to solve - estimation and adding up - 4th grade math

Here are two money-related word problems for about 4th grade. The first one asks how many $0.89 toy figures you can get with $15, which would normally be solved with division, but here we solve it using doubling and estimation.

The second problem is a simple subtraction problem, BUT we find it's quicker to solve it using adding up. Mental math beats the regular subtraction algorithm here!