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## How Old is Grandpa

Math brain teasers require computations to solve.

 Puzzle ID: #1404 Fun: (2.54) Difficulty: (2.51) Category: Math Submitted By: gokaran

Grandpa says, "My grandson is about as many days as my son is weeks, and my grandson is as many months as I am in years. My grandson, my son and I together are 100 years. Can you tell me my age in years?"

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 cat Dec 12, 2001 neato make more!!!!!!!!!!!!!!!!!!!!! :] pusandave Mar 29, 2002 I am impressed with your ability to explain the answer. It's nice to see it spelled out instead of just "60". paul726 Mar 05, 2006 I agree with liking to see the answer explained, but I don't think so much detail was necessary. tonjawithaj Aug 09, 2006 This one made me think! jasmin215 Oct 29, 2007 WOW! i gave up after i tried it for like 2 mins and after that respose lol gave up even quicker. it sounds right t me since you had a long explain.. must be right good job!!!!!!! javaguru Feb 08, 2009 There is a MUCH easier way to do this--I did this in under 10 seconds in my head. The ratio of ages is 12::7::1. 12+7+1=20. 100/20=5. 5*12=60. This works for all these ratio problems. Setting up equations is a waste of time. Jimbo Apr 15, 2009 If I am x years then my grandson is x/12 years and my son is (x/12)*365/52 which is approximately 7x/12. Thus x + x/12 + 7x/12 = 100 or x = 60. The diffiiculty here is to realise that there are about 7 times as many days as weeks in a year. I like Java's solution better. bookrage Jan 30, 2015 hardest puzzle I've solved to date. I just created an account yesterday but have been coming here for years. Challenging and actually requires a lot more algebra than a lot of stuff here. Liked it. I had to set up the equations to make the problem make sense but did the calculations in my head once I figured out how the problem worked. nice challenge though.