824*126. It's easier to multiply by the smaller number, which is 126. We take the last digit, 6, first and multiply 824 by it: 4944. Write that down. Now we take the 2 and multiply 824 by it but we put a zero on the end of the result: 16480. Write that down to be added to 4944. Finally we take the 1. But we don't need to multiply this time, but we do need to add another 0 to the result: 82400. We add that in 4944+16480+82400=103824. If you lay your work out as below you'll find it a lot easier to add up.
824
126 X
4944
16480
82400
103824