Curriculum › Math ›Grade 6

Grade 6 Math · Level 2, Ratios, Rates & Percent

Find the Whole from a Part and Percent

How the lesson starts: Find the Whole from a Part and Percent

1. Captain Nova's fuel tank

   Hi there! Captain Nova's rocket is getting ready for launch. The fuel gauge says 20%, and the crew measured 18 liters in the tank. So how much does the whole tank hold? This time we know the part, and we need the whole. Let's work backwards!

2. Draw a bar

   Draw the tank as a bar. 20% is 1/5, so cut the bar into 5 equal parts. One part is 18 liters. The whole tank is all 5 parts: 5 × 18 = 90 liters. The whole is always bigger than its part!

3. Let's work one out

   12 is 25% of what number? As an equation, that's 0.25 × x = 12. 25% is 1/4, so 12 is one fourth of the whole. The whole is 4 fourths: 4 × 12 = 48. Watch out: 25% of 12 is 3, but that's smaller than the part. Wrong way!