Hi! I'm Sean with Expert Village and I'm going to show you tips and tricks for doing math in your head. When dealing with large numbers, it's best to think of them in blocks. We like to deal with multiples of 10 because they're easy to handle. If we had for example, 72-47, it's easier to think of it as (70+2)-(40+7). We can subtract the 40 easily enough from the 70 leaving us with (30+2)-7. We can then subtract the 7 from the 30, leaving us with 23+2, which adds up to 25 for our answer. Doing it this way is very simple because we're only dealing with easy to add and subtract numbers. Whenever you're doing math in your head, the most important part is being able to visualize the numbers. The more you practice, the better you're going to get.
