A few strategies for calculating 15% of 48 (Students may have many others.)

Strategy 1:

10% of 48 is 4.8.
5% of 48 is half of this, or 2.4.
4.8 + 2.4 = 7.2

 Strategy 2:

48 ÷ 100 = 0.48 is 1% of 48.
15% of 48 is 15 times this amount.
15 • 0.48 = 7.2

Strategy 3:

15% of 48 is 15 hundredths of 48.
(15 / 100) • 48 =  (15 / 100) • (48 / 1) = 720 / 100 = 7.2

Strategy 4:

15% is 15 / 100, which simplifies to 3 / 20
3 / 20 of 48 is 48 ÷ 20 • 3 = 2.4  • 3 = 7.2

Strategy 5:

25% of 48 is 1/4 of 48, which is 12.
10% of 48 is 4.8.
15% = 25% – 10%
12 – 4.8 = 7.2

Strategy 6:

Write 15%  as a decimal and multiply it by 48.
0.15 • 48 = 7.2.

Strategy 6 is probably the most traditional, but other strategies may be more likely to come from students' understanding of percentages, fractions, and decimals.