maths quiz

[PearsonP]

if 11 squared is 121 and 111 squared is 12321.

what the square root of 12345678987654321?

p.s. i alredy know i'm testing you!

[smouse]

just because I am so pleased to be the first to answer for a change

111111111

[SFD1968]

111,111,111

[fozzie]

111111111   ie Nine ones in a row.

The middle or highrst number of the square of any series of ones (eg 11, 111, 1111 ...etc up to nine ones) is the actual number of ones in the square root - if you see what I mean ?

In your question the middle ( or highest number ) is 9 - Hence the answer is 111111111