Number Sense Blog

    Word Problem Wednesday: The Birthday Candle Challenge

    By Mathnasium | Added Dec 26, 2018

    Use elementary math skills such as fractions, decimals, addition, subtraction and multiplication to solve this week’s birthday-themed word problem challenge.

    🎵 Happy birthday to you, happy birthday to you... 🎵

    How old is Barb? Sometimes it’s just not proper to ask someone how old they are. Luckily, we have birthday cakes specifically designed to let you know how old someone is...with candles! You don’t have to go to a math tutor center to count candles, but we think it’s more fun to serve a little challenge along with your birthday cake.

    Take a look at this week’s word problem challenge. You’ll need to use your elementary math skills such as fractions, decimals, addition, subtraction and multiplication. Take your time working it out. When you're ready, check below for the solution!

    🎂 Question: Barb’s birthday cake has 1 more candle than the number of years she has been alive. If 1/2 of the candles are blue, 1/3 of the candles are green, and the remaining 4 candles are yellow, then how old is Barb?


    Solution: In order to compare the fractional parts, we need to give them the same denominator – in this case, 2 × 3 = 6. 1/2 × 3/3 = 3/6 of the candles are blue, and 1/3 × 2/2 = 2/6 of the candles are green. This means that 3/6 + 2/6 = 5/6 of the candles are blue or green, leaving 1 – 5/6 = 1/6 of the candles yellow. If 1/6 of the candles is the same as 4 candles, then the whole number of candles must be 6 × 4 = 24. If there is 1 more candle on the cake than the number of years Barb has been alive, then she is 24 – 1 = 23 years old.





    Find Your Local Mathnasium


    Subscribe to Email Updates



    Before I came to Mathnasium, I could sum up everything I felt about math in one word: 'EVIL!' I hated math. ... Mathnasium has been my safe haven. They truly have shown me the light when it came to addressing my fear and provided me with the tools that I need to rebuild my prior knowledge so that I won't forget it. Math is no longer a subject I shy away from but it is a subject I can boldly accept and understand.

    Roxanne, 12th grade