Archive for the ‘Multiplying by 11’ Category

Multiplying by Eleven? Discover Fun, Easy Patterns!

Wednesday, May 12th, 2010

number-11.

Everyone loves multiplying numbers 1-9 by 11 because of their fun, double-number patterns:  11, 22, 33, 44, 55, 66, 77, 88 and 99.

For two-digit numbers, add the first and second digits and place the answer between these.  Example:  45 x 11 = ___.

·         Four plus five is 9.

·         Place 9 between 4 and 5.

·         The answer is 495.

When the sum of the first and second digits is greater than 9, increase the left-hand number by 1.  Example:  28 x 11 = ____. 

·         Add the first and second digits:  2 + 8 = 10. 

·         Add the 1 to the 2:  1 + 2 = 3.

·         Place the 0 between 3 and 8. 

·         The answer is:  308.

By teaching children these fun, easy patterns, we will instill in them a love of numbers and fascination with math.