Math:
Students have been learning to find the digital root of numbers to help them know if a number is a multiple of a certain factor. (The reverse is this is divisibility rules.)
What is a digital root you ask? To find the digital root of a number you simply add the digits of that number together until you find its single “digit root”. For example, 27 becomes 2 + 7 = 9. Nine is the digital root of 27. The digital root of 39 is 3 + 9 = 12, 1 + 2 = 3, so the digital root of 39 is three. So how does this help us in math you ask. We have found that all multiples of three have a digital root of 3, 6 or 9. So is 423 a multiple of 3? Find the digital root to find out. (This also will help you know if 423 can be divided equally by 3.)
There are some other interesting patterns that emerge when finding the digital root of other numbers. For instance take the first 10 multiples of 9 ( 9, 18, 27, …) and find the digital root. What do you notice? Can that help you when learning the basic facts for nine? How about a general rule for the multiples of nine? What about when dividing by nine? Ask your child to show you some of the other patterns they found when they plotted their digital roots on a 9-point circle.
Posted on October 29th, 2008 by palanib
Filed under: Uncategorized