AR · 8 cards

Turning Words into Math flashcards

8 cards with the formulas, rules and traps from this lesson. Answer in your head, then flip to check.

Common trap · 1/8
How do you translate '8 less than a number' into math?
$x - 8$ : start with the number and take 8 away. Writing $8 - x$ reverses the order and is a classic trap.
Rule · 2/8
Write and solve: 'Seven more than twice a number is 31.'
$2 x + 7 = 31$ , so $2 x = 24$ and $x = 12$ . 'Is' becomes the equals sign; build 'twice a number' first, then add 7.
Rule · 3/8
When do you need parentheses when translating words into math?
When the words say to combine first. 'Twice the sum of a number and 7' is $2 (x + 7)$ , not $2 x + 7$ .
Strategy · 4/8
Instead of hunting keywords, how do you pick the operation?
Ask what the story does to the quantities: combining or increasing means add; removing, comparing or finding a missing part means subtract; equal groups or rate times time means multiply; equal sharing or finding a rate means divide.
Common trap · 5/8
How many hours is 1 hour 15 minutes?
1.25 hours, not 1.15. Minutes are sixtieths of an hour, so $15 \div 60 = 0.25$ hour.
Common trap · 6/8
A count fell 40 percent to 270. How do you find the original count?
What is left is 60 percent of the original: $0.60 x = 270$ , so $x = 450$ . Adding 40 percent of 270 (giving 378) is the trap.
Strategy · 7/8
What are the six steps of the AR translation routine?
Note what is asked and its unit; name the unknown; keep only the facts linked to it; translate into an equation, converting units first; estimate the size and direction; calculate and check against the question and choices.
Common trap · 8/8
Why reread the question sentence before picking an answer?
Intermediate subtotals often appear among the choices. Make sure your number is the final quantity asked for, such as the change from 100 dollars rather than the 54 dollar cost.

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