n number of the digit 1 square. Calculating without a calculator or computer

by: Joe Hing Kwok Chu

Another math trick you can use to fool your math teacher.

n number of the digit 1 square.

1²

11²

111²

1111²

^{It is like this:}

^{If the number of digit is n}

1×1＝1
 n is 2 ---->   11×11＝      121
 n is 3 ---->   111×111＝    12321
 n is 4 ---->  1111×1111＝  1234321
 n is 5 ---->  11111×11111＝123454321

From the above pattern, if there are n number of 1 multiplying by itself (square), then the answer will be:      1234…n…4321