SME
Grade 6 Math · Ratios & Proportions
Understand and use percent
Use this for “What is 25% of 80?” and to find the whole from a part and its percent.
Diagram
25% of 80 is 20.
1% is 0.8.
This is an example. Type your own values to start a new problem.
p
%
of
w
=
x
One percent of the whole
worked out (not typed)
Formulas
80 ÷ 100 = 0.8
Whole ÷ 100 = one percent
0.8 × 25 = 20
One percent × percent = part
Assumptions
•
Percent means out of 100: the whole is 100%.
•
More than 100% means more than the whole.
•
The part and the whole use the same unit.
•
Give any two of part, whole and percent to find the third: the whole from a part and its percent too.
Step-by-step
WE KNOW
Percent: 25%
Whole: 80
FIND
one percent of the whole, part
Step 1 · Find one percent of the whole
80 ÷ 100 = ?
Whole ÷ 100 = one percent
The whole is 100%. Share it into 100 equal parts to find 1%.
One percent of the whole = 0.8
Step 2 · Find part
0.8 × 25 = ?
One percent × percent = part
The part is that many of the one percent.
Part = 20
Check
Put the numbers back in. Both sides should match.
0.8 × 100 = 80 ✓
0.8 × 25 = 20 ✓
Topic check
See what you know: 5 questions on this topic
New questions each time. Pass to mark it complete.