به انگلیسی

Adding and subtracting big numbers in your head

ریاضی · جمع و تفریق · سن ۹ تا ۱۰ سال

نام ______________________ تاریخ ____________

What is 2,500 + 2,600?
- 4,100
- 6,100
- 5,100
- 5,000
What is 45,000 + 8,000 mentally?
- 48,000
- 53,000
- 52,000
- 43,000
What is 45,000 + 8,000?
- 52,000
- 53,000
- 54,000
Counting up from the smaller number is one way to subtract in your head.
دور یکی دایره کشیدن: درست نادرست
Ava doubled 2,500 to get 5,000, then added 100 to reach 2,500 + 2,600. Is her method right?
دور یکی دایره کشیدن: درست نادرست
Use a near-double to solve 3,400 + 3,500.
- 6,900
- 6,800
- 7,000
Count up from 3,200 to 10,000. How far is it?
- 7,800
- 6,200
- 13,200
- 6,800
What is 10,000 - 3,200?
پاسخ: ______________
Omar says 4,700 − 1,300 = 3,300. Is he right?
- Yes, 3,300 is right
- No, the answer is 3,400
- No, the answer is 3,500
Jay says 45,000 + 8,000 = 53,000 because 45 + 8 = 53. Is Jay right?
دور یکی دایره کشیدن: درست نادرست

پاسخ‌نامه

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5,100 · 5,100 is right: double 2,500 to get 5,000, then add the extra 100.
53,000 · 53,000 is right because 45 + 8 = 53 thousands.
53,000 · 45 thousand + 8 thousand = 53 thousand, so the answer is 53,000.
درست · Counting up from the smaller number to the bigger one tells you the gap between them, which is the answer.
درست · Ava is right: 2,600 is 100 past the double, so 5,000 + 100 = 5,100.
6,900 · 3,400 + 3,400 = 6,800, and 3,500 is 100 more than 3,400, so add that 100: 6,800 + 100 = 6,900.
6,800 · 6,800 is right because 3,200 + 6,800 = 10,000.
6800 · 10,000 - 3,200 = 6,800.
No, the answer is 3,400 · Subtract the thousands and hundreds separately: 4,000 − 1,000 = 3,000 and 700 − 300 = 400, so the answer is 3,400.
درست · Jay is right: thousands add like ones, giving 53 thousands.