19 is only 1 away from 20, so you prefer to start by multiplying 20 times 5, which equals 100. Then we need to take away a squadron of 5, because there are actually only 19 squadrons, not 20. 100 take ...

It's possible to solve some multiplication problems in your head. But sometimes it can help to use other methods instead. These include using visual aids, such as an array or place counters, or by ...

In 1971, German mathematicians Schönhage and Strassen predicted a faster algorithm for multiplying large numbers, but it ...