So, forgive me if this is old news to you. It is quite old news anyway, as it goes: it was invented by the Chinese a long time ago. Like a lot of ancient wisdom, it totally works.
Plus it's much easier than the confusing method Mrs Canterbury taught me in Year 8 maths.
"You won't always have a calculator in your pocket!" she proclaimed to us in 1991.
So, Mrs Canterbury, this one's for you.
Q: What is 37 x 13?
1. Draw a grid where the number of rows and columns match the number of digits you need to write down the problem. Write the first number as digits in the column headings, and the second number as digits in the row headings.
2. Multiply each row and each column and fill in the grid. The boxes should never be higher than 9x9 so as long as you know your times tables, you'll be grand.
3. Separate the grid into diagonals which run bottom left to top right.
4. Add up the numbers in each diagonal channel and order them left to right.
6. If there are two-digit numbers in your answer, start at the right and shunt the left digit of each number across to the adjacent number on the left. The carried-across digit always adds itself to the right digit of the box on its left. Always do this right to left.
7. You are allowed two digits in the leftmost number. When all your digits have carried across, whatever you're left with is the result! Boom!
It works for larger numbers too. Split them into diagonals, add the diagonals together, shunt the units across and you'll have the right answer.
Q: What is 1344 x 237?
Enough to bring you out in a cold sweat. Not with the grid method though:
... or just maybe take your phone with you.
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