Multiplication of a number consisting of only ones with another number becomes very easy using Vedic Maths techniques. You must see the earlier post on shortcut for multiplying a number by 11
MULTIPLYING A NUMBER BY 111
To multiply a two-digit number by 111, add the two digits and if the sum is a single digit, write this digit TWO TIMES in between the original digits of the number. Some examples:
The same idea works if the sum of the two digits is not a single digit, but you should write down the last digit of the sum twice, but remember to carry if needed. So
because 5+7=12, but then you have to carry the one twice.
For 3 digit numbers
Carry if any of these sums is more than one digit.
Thus 123×111 = 1 | 3 (=1+2) | 6 (=1+2+3) | 5 (=2+3) | 3
241×111 = 26751
For an example where carrying is needed
Say, 352×111=3 | 8 (=3+5) | 10 (=3+5+2)| 7 (=5+2)| 2
= 3 | 8 | 10 | 7 | 2 = 3 | 9 | 0 | 7 | 2
(Because of the carries, it may be easier to do the sums and write the answer down from right to left.)
Let me know, if you liked this Vedic Maths trick.