Sometimes, a division calculation is "close" to being something extremely easy. For example, the calculation \(495 \div 5\) is very close an easily calculated \(500 \div 5\text{.}\) But since it’s easy to see that \(500 \div 5\) is and that is one group of less than it is not too difficult to see that \(495 \div 5 = 99\) (1 group short of 100 groups of 5).
This method of finding approximate answers and adjusting is commonly done in mental arithmetic when it’s possible. But it’s a good way to quickly calculate the answer in those situations.
Practice your mental arithmetic by performing the following calculations.
It’s not always the case that the number will be "one away" from a nice value. Sometimes, it may be two or three away. But with some practice and experience, you can learn to spot those values, too.
Practice your mental arithmetic by performing the following calculations.
Sometimes the "nice" value isn’t quite as nice, but is still helpful. Instead of being near a multiples of these are examples that are near multiples of The same ideas still apply. These are a bit trickier because you really need to be comfortable with your multiplication table to do itself.
