Determine the smallest 3-digit number N such that the tens digit of N^2 is 7.
Determine the smallest 3-digit number N such that the tens digit of N^2 is 7.
sushantkataria @ PaGaLGuYAlways consider the squares of two digit number in such cases because even if you square a 3 digit number the last two digits remain the same.For example. consider 11^2=121 and 111^2=12321.In both cases last two digits are same i.e 21.So coming back to the question if you remember the squares of two digit numbers up to 30 properly the first number to have 7 as its tens digit is 24 i.e 24^2=576.So 124 is the smallest 3 digit number such that the square of this number has 7 as its tens digit.(124^2=15376).There are some other methods also to solve this problem but according to me this one is the fastest method.