5 Tips for Quick Mental Division

Do you avoid solving long division problems simply because they are lengthy, time consuming, and scary? Here are 5 quick mental division tips that will see you through!

Mental division tip #1 – Accuracy is not always a priority

Very often, division answers are in two to three decimal places. Don’t waste time on detailed calculation if it’s a ballpark estimate that you require. In such cases, make a quick high-level estimate and get your answer. Let’s say you have to calculate the average number of days you have in hand to complete each of your projects – 11 projects in 123 days. Here is the trick: 11 is close to 10 and 123 close to 125. So, instead of calculating 123 / 11, figure out 125 / 10! The approximate answer - 12.5 - will not be very distant from 11.1, your accurate answer.

Mental division tip #2 – Simplify first

What do you do when approximate answers aren’t good enough? Here are a few useful simplified division tips:

If the dividend and divisor are both even numbers, try dividing them first by 2. For example, if you’ve got to divide 196/22, divide them by 2 first. When you have 98/11, you’ll find it easier to figure out the rest of it with the smaller numbers.

If the divisor and dividend are not even numbers, then try dividing them by their smallest factor. Say, for example, you have to divide 99 by 21. Divide them by 3 (smallest factor) and you’ll have 33/7, which is simple enough to be divided further!

Mental division tip #3 – Multiply to simplify

No matter how paradoxical the mental division tip #3 might sound, it’s extremely useful! The secret is to multiply before we divide. Instead of dividing 1525 by 5, multiply 5 and 1525 with 2! Once your divisor is 10, it will be easy for you to figure out the rest.

Mental division tip #4 – Split dividend

Split either the dividend (that's the number you're dividing) or the divisor (that's the number you're dividing by) to make the division problem simpler. If you’re dealing with a complex dividend, example 54, split it into a sum of numbers that are each divisible by their least common factor, 3 (the divisor) in this case. Divide 24 + 30 (sum is equal to 54) by 3 and you’ll have a much easier division problem at hand.

Mental division tip #5 – Split divisor

Instead of splitting up the dividend into a sum, split the divisor into a product. Let’s take 324 / 6 as an example. Split 6 into two factors, 2 and 3 in this case. Once you've split up the divisor, you're free to divide the dividend by any of the factors in whatever order is most convenient. First, divide 324 by 3 which equals to 108. Divide 108 by 2 and you’ll have 54, the answer to 324 / 6! Easy, isn’t it?

Divide and rule with these simple mental division tips!