By Ole Steen Hansen

Marking the a hundredth anniversary of the Wright brothers' first flight,

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The giant golden book of mathematics : exploring the world of numbers and space

An evidence of the technology of numbers and house, with easy demonstrations of mathematics, algebra, trigonometry, arithmetic in tune and paintings, and together with a few methods and video games utilizing numbers.

Additional resources for Military Aircraft of WWI

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3 weeks 6 days Ϫ 2 weeks 2 days 4 days Subtract weeks. 3 weeks 6 days Ϫ 2 weeks 2 days 1 week 4 days You will have 1 week and 4 days left. 40 Time Let’s do one that uses hours and minutes. 12 hours 37 minutes Ϫ 6 hours 16 minutes Subtract minutes first. 12 hours 37 minutes Ϫ 6 hours 16 minutes 21 minutes Subtract hours. 12 hours 37 minutes Ϫ 6 hours 16 minutes 6 hours 21 minutes 41 Subtraction L ook at the question “You have 9 oranges. ” The words left and take away tell you that you should subtract.

Subtract the number of points the score was decreased by from last week’s score. 32,000 score last week Ϫ 4,000 decrease in score 28,000 score this week 4 Check your work. Make sure you have answered the right question. Remember, you can use addition to check your subtraction. 28,000 ϩ 4,000 ϭ 32,000 45 Further Reading Cato, Sheila, and Sami Sweeten. Subtraction. Minneapolis: Carolrhoda Books, 1999. Creative Teaching Press. Addition and Subtraction Facts to 20. : Creative Teaching Press, 2002. Leedy, Loreen.

R ounding to a smaller place value gives a closer estimate than rounding to a larger place value. A. Estimate 637 Ϫ 82 to the hundreds place. Write the numbers in columns. Round each to the nearest hundreds. 637 rounds to 600 Ϫ 82 rounds to 100 Subtract. 600 Ϫ 100 500 B. Estimate 637 Ϫ 82 to the tens place. Write the numbers in columns. Round each to the nearest tens. 36 637 rounds to 640 Ϫ 82 rounds to 80 Exact Difference 5 14 Subtract. Regroup 1 hundred as 10 tens. 640 Ϫ 80 560 C. Find the exact difference.