When estimating I advise rounding the numbers offered down or upto the closest value as a 5 or a 10.
So lets take 6 and call it 5
and make 256 say 260
so 260 x 10 is easy that’s add a 0 to give 2600 so we want half of this as our estimate since we only want to multiply by 5.
So our answer should be in the order of 1300