Question 29

The last two-digits in the multiplication $$122 \times 123 \times 125 \times 127 \times 129$$ will be

Solution

While finding the last 2 digits, we can ignore the hundredth digit of each number and the last two digit will be the same as last two digit in case of $$22\times\ 23\times\ 25\times\ 27\times\ 29$$.

25*22= 550, which is an important result. 

The rest numbers, 23, 27 and 29 when multiplied by 550, will result in the same last 2 digits as odd number multiplied by 5 will always give 5 as the last digit and we already have 0 at the end of it. So, odd number* 50= X50 always.

So, the last 2 digits will always be 50.

Video Solution

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