Find the largest four-digit value of such thatis an integer.

Put the expression equal to N (an integer) and square it.

That gets you N^2 = t- N or, t = N^2 + N.

The largest integer value for N that can be substituted so that t is still a 4 digit numbe is 99 and that gets

you t = 9900.

That is really neat Bertie

Yes it is !!!!