To multiply together 11 times any number:     ex.    11×7421=631

-The ones digit of the number being multiplied by 11 is the ones digit of the answer.     ex.   the ones digit of 7421 is 1, and this is the ones digit of the answer.   _ _ _ _ 1

-Pair and add the last two digits of the number being multiplied by 11. This yields the tens digit of the answer (there may be a figure to carry).    ex.   adding the last digit pair of 7421 gives the tens digit of the answer.   2+1= _ _ _3_

-Add each successive digit pair in the number being multiplied by 11 (plus any carry figures, if any) to give the next successive number of the answer.     ex.   adding the next digit pair of 7421 gives the hundreds digit of answer.   4+2=_ _6_ _

-Continue in this manner adding successive pairs for successive digits of the answer (plus any carry figures, if any).     ex.   adding the next digit pair of 7421 gives the thousands digit of the answer.   7+4=_1_ _ _  (carry 1)

-*When there are no more digits available in the number being multiplied by 11 to pair, simply use the left-most digit that is unpaired for the first digit of the answer.    ex.  The digit left without a pair for 7421 is 7,and this plus the carry figure is the first digit of the answer.   7+(carry figure of 1)= 8_ _ _ _

*I like to consider that the left-most digit having no available pair is paired with 0, but this is optional. This helps me remember to not forget it- I’m not through until I’ve paired a number with 0. Try it with and without pairing the left-most digit with 0, and see which way you prefer.

See how easy these are:    421×11=4631     295×11=3245     230×11=2530