* Whiteboard required
** This activity is teacher paced
Learn how you can square large numbers in your head - instantly! This easy to learn technique will have you calculating the square of numbers up to 100 - without the need for a calculator.
The trick is easy - first we find the distance from the number being squared to the nearest tens number. Say for example we are trying to find the square of 23 - the nearest tens number is 20, which is 3 away from 23. So 3 is our result!
We use this number to find the square - by taking this number from the number being squared (23 - 3 = 20) and then adding this number to the number being squared (23 + 3 = 26). We easily multiply these two numbers (20 x 26 = 520).
To this we add our distance number squared (3 x 3 = 9). So we add 9 to 520...our answer is 529.
Love the math!
The old math is dead! Long live the math!