Teacher2Teacher Q&A #1154

Teachers' Lounge Discussion: Front End Estimation

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From: Julian

To: Teacher2Teacher Public Discussion
Date: 2001010422:35:28
Subject: Give me a break!

"5.45 +6.49, 7.48, 2.42, and 1.49, rounding would get me the answer to 5 + 6 + 7 + 2+ 1, or 21. "With front end estimation I would add the whole numbers, getting \$21, and then refine that estimate by noting that there are about \$2.50 more there, for an estimate of \$23.50. The actual sum is 23.33." I can't believe this came from a Swarthmorian-LOL. You're not explaining front end estimation. If I were rounding, I would also round the pennies afterwards (especially if they were in the 50 cents range). You have to do better than that Gail. Regular rounding would get me an answer of between 23 and 24 dollars too. (21+2.50) Whoever invented front end estimation should be locked up and put away. The 4th grade teachers have a hard time explaining it, and worse yet the students don't have a clue. Rounding should be the only method taught. It's simple, direct and the students-understand the concept. The reference you put on top is exactly the way I told my son to do a problem. It would have been marked WRONG because 21 was the answer the teacher would have been looking for! Altough the answer given of 23.5 was more accurate, and was achieved more easily through rounding. Rounding(5.50+6.50+7.50+2.40+1.50)=\$23.40(rounding from cents column). I tell my son the smaller the number the more accurate the rounding has to be. 999,930 = 1,000,000 .04 =.05 In short, I agree with the PTA member!

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