00:00You've got 99 problems but your dad ain't one. Here's a Father's Day math trick to turn your dad's digits
00:04into an ice cream.
00:05First, write down the year your dad was born.
00:08Next, reverse the digits and take the smaller number away from the larger one.
00:11Add the digits in this number together.
00:14Multiply this by the number of letters in your dad's birthday month.
00:17Again, add up the digits of your answer.
00:19And finally, multiply your answer by 11.
00:21Now put a flake in it, you're done!
00:24You should have mathed up a 99.
00:26And the hidden maths of why this works all revolves around the number 9.
00:29Take any number however long and add its digits.
00:32If this sum is in the 9 times table, the first number must also be in the 9 times table.
00:37If it is and you continue to add the digits of each sum until your answer is just one digit
00:41long, that number will always be 9.
00:43For hardcore maths geeks like me, you can use algebra to see exactly why this works.
00:48For everyone else, happy Father's Day!
00:50Now go try this on your dad.
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