How do you estimate front end digits?

Front end estimation generally produces a better estimate of sums or differences than rounding before adding or subtracting. How to Estimate a sum by front end estimation * Add the digits of the two highest place values * Insert zeros for the other place values

* Example 1: 4496 + 3745 is estimated to be 8100 by front end estimation (i.e. 4400 + 3700). * Example 2: 4496 + 745 is estimated to be 5100 by front end estimation (i.e. 4400 + 700).