MENTAL ARITHMETIC: MULTIPLICATION

PROBLEMS (3)

Do the problem yourself first!

 20. Rounding off a) Calculate in writing by distributing 2 to this difference: 3 × (600 − 2) = 1800 − 6 = 1794 b) Multiply mentally:  3 × 598 = 1794

21.   Multiply each column mentally.  Treat problems with decimal points
21.   as dollars and cents.

 6 × 99 = 594 2 × 2.95 = 5.90 7 × 11.98 = 83.86 5 × 79 = 395 3 × 4.95 = 14.85 5 × 16.96 = 84.80 3 × 89 =  267 6 × 5.98 = 35.88 7 × 24.98 =  174.86 8 × 39 =  312 5 × 7.99 =  39.95 3 × 19.95 =  59.85

Can you do these mentally, or with the least amount of writing?

22  At a political fund raising, fifty people paid \$10,000 each to have
22. dinner with the President.  How much money was raised?  \$500,000

23.  If your car gets 25 miles per gallon, how far could you go on 12
23 . gallons?  12 × 25 = 250 + 50 = 300 miles.

24.  What is the price of 4 airline tickets at \$182 each?   \$728

25.  What is the price of 6 airline tickets at \$56.98 each?  \$341.88

25.  What is the price of 60 tickets?  \$3,418.80

26  If coffee sells for \$3.95 a pound, what is the price of 4 pounds?
26.   \$15.80

26.  What is the price of 40 pounds?  \$158

27.  a)  How many days are there in 10 years?  Approximately 3,650.

27.  b)  How many days are there in 2 years?

27.   b) 2 × 365 = 600 + 120 + 10 = 730

27.  c)  How many days are there in 12 years?  3,650 + 730 = 4,380

Continue on to the next Lesson.

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