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Use of Equal Sign

Use of Equal Sign. Approximate Sign vs Equal Sign. When do we use ‘ ≈’ or ‘= ’ in our number statements ?. Which is correct?. . 1 678 is not the same as 1 680. 1 678 = 1 680. or. . 1 678 ≈ 1 680. 1 680 is an approximate value of 1 678. Therefore ‘≈’ must be used.

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Use of Equal Sign

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  1. Use of Equal Sign

  2. Approximate Sign vs Equal Sign When do we use ‘≈’ or ‘=’ in our number statements?

  3. Which is correct?  1 678 is not the same as 1 680. 1 678 = 1 680 or  1 678 ≈ 1 680 1 680 is an approximate value of 1 678. Therefore ‘≈’ must be used.

  4. Which is correct? 6 345 m is an exact value of 6  345 m. Therefore ‘=‘ must be used.  6  345 m = 6 345 m or  6  345 m ≈6 345 m 6 345 m is not an approximate value of 6  345 m.

  5. Using unitary method to solve word problems E.g. 40% —— $1 600 10%—— 1 600 ÷ 4 = $400 100% —— 10 x 400 = $4 000 40% = $1600 100% = $4 000        This is because amount of money is not the same as %.

  6. Ali and Shawn have a total of 210 stamps. Shawn has twice as many stamps as Alan. How many stamps does Shawn have? 3 units —— 210 1 unit —— 210 ÷ 3 = 70 2 units —— 2 x 70 = 140 Shawn has 140 stamps.     

  7. Dollar and cent notation Muthu bought a pen for 40 ¢and a book for $1.40. How much did he spend altogether? Amount spent altogether = $1.40 + 40 ¢ = $1.40  

  8. Dollar and cent notation Muthu bought a pen for 40 ¢ and a book for $1.40. How much did she spend altogether? Amount spent altogether = 1.40 + 40 = $1.80 

  9. Conversion of unit of measurements during intermediate steps E.g. 52 litres = 52 000 cm3 52 litres = 52 000 52 litres ——52 000   Units missing 

  10. John gave of his stamps to Peter. If he gave 16 stamps to Peter, how many stamps did he have at first? = 16 A fraction is not equal or the same as a whole number!   1 = 8 x 16 = 128 Note : The answer may be correct but the method is wrong and therefore no mark will be awarded.

  11. —— 16 BUT  Here the fraction represents a whole number.  1 —— 8 x 16 = 128 Or we can also use the unitary method :  1 unit —— 16 8 units —— 8 x 16 = 128  John had 128 stamps at first. 

  12. Write as a percentage. Percentage Many pupils will do this:  Why? = = 75% • This is incorrect because • % is missing! • is not the same as itself x 100 !

  13. Write as a percentage. SO  = = 75% Or we can also use the unitary method :  4 units —— 100% 3 unit —— = 75% 

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