Subtracting from the Whole Number
Subtracting from the Whole Number is a Grade 5 math skill in Eureka Math, Chapter 16: Making Like Units Pictorially, where students learn to rewrite a whole number as a fraction before subtracting a fraction with like or unlike denominators, using rectangular models to visualize the regrouping process.
Key Concepts
To subtract a fraction from a mixed number between 1 and 2, you can decompose the mixed number, subtract the fraction from the whole number (1), and then add the remaining fractional parts. For a problem in the form $1 \frac{a}{b} \frac{c}{d}$, the process is: $$(1 \frac{c}{d}) + \frac{a}{b}$$.
Common Questions
How do you subtract a fraction from a whole number?
Rewrite the whole number as an equivalent fraction with the same denominator as the fraction you are subtracting. For example, to compute 3 - 2/5, rewrite 3 as 15/5, then subtract to get 13/5.
Why do you need to rewrite the whole number as a fraction?
Subtraction requires like units. Since you cannot directly subtract 2 fifths from a whole, you convert the whole number into fifths so both quantities share the same unit.
What is the pictorial strategy for subtracting a fraction from a whole?
Draw a rectangular model of the whole number, partition the last whole unit into sections equal to the denominator, then cross out the sections being subtracted to show the remaining amount.
What is Eureka Math Grade 5 Chapter 16 about?
Chapter 16, Making Like Units Pictorially, teaches students to add and subtract fractions with unlike denominators using area models and rectangular fraction diagrams.