OK, let's crack this. We're given 503 and our task is to multiply it by 26. Essentially, we'll be adding 503 to itself 26 times.
Step 1: 0 + 503 = 503
Step 2: 503 + 503 = 1006
Step 3: 1006 + 503 = 1509
Step 4: 1509 + 503 = 2012
Step 5: 2012 + 503 = 2515
Step 6: 2515 + 503 = 3018
Step 7: 3018 + 503 = 3521
Step 8: 3521 + 503 = 4024
Step 9: 4024 + 503 = 4527
Step 10: 4527 + 503 = 5030
Step 11: 5030 + 503 = 5533
Step 12: 5533 + 503 = 6036
Step 13: 6036 + 503 = 6539
Step 14: 6539 + 503 = 7042
Step 15: 7042 + 503 = 7545
Step 16: 7545 + 503 = 8048
Step 17: 8048 + 503 = 8551
Step 18: 8551 + 503 = 9054
Step 19: 9054 + 503 = 9557
Step 20: 9557 + 503 = 10060
Step 21: 10060 + 503 = 10563
Step 22: 10563 + 503 = 11066
Step 23: 11066 + 503 = 11569
Step 24: 11569 + 503 = 12072
Step 25: 12072 + 503 = 12575
Step 26: 12575 + 503 = 13078

So, 503*26 = 13078