@audrey One more thing...
"Notice that since a, b, c, and d are all less than or equal to five, the sum of each column will be less than 10. Then we can look at the digits of 14762 and directly see which of a, b, c and d were added together to get it. "
Should be:
Notice that since a, b, c, and d are all less than or equal to five, the sum of each column will be less than or equal to 10. Then we can look at the digits of 14762 and directly see which of a, b, c and d were added together to get it.
