Задача Задача №3670671
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Answers
Short answers
1. Divisibility tests
| Part | Answer | Check |
|---|---|---|
| a | Yes | \(1275 \div 5=255\) |
| b | Yes | \(3141 \div 9=349\) |
| c | Yes | \(21648 \div 8=2706\) |
| d | Yes | \(43572 \div 6=7262\) |
| e | Yes | \(38520 \div 10=3852\) |
| f | No | \(512617 \div 3=170872\) remainder \(1\) |
| g | No | \(48020 \div 100=480\) remainder \(20\) |
| h | Yes | \(418 \div 2=209\) |
| i | Yes | \(4864 \div 4=1216\) |
| j | Yes | \(58750 \div 250=235\) |
3. Prime numbers
The prime numbers are:
\[ \boxed{67,\ 97,\ 127} \]
4. Multiples of \(7\)
- \(301=7\times43\) — Yes
- \(408=7\times58+2\) — No
- \(18088=7\times2584\) — Yes
Key rules
- Divisible by \(2\): the last digit is even.
- Divisible by \(3\) or \(9\): the sum of the digits is divisible by \(3\) or \(9\).
- Divisible by \(4\): the last two digits are divisible by \(4\).
- Divisible by \(5\): the last digit is \(0\) or \(5\).
- Divisible by \(6\): the number is divisible by both \(2\) and \(3\).
- Divisible by \(8\): the last three digits are divisible by \(8\).
- Divisible by \(10\): the last digit is \(0\).
- Divisible by \(100\): the last two digits are \(00\).
- Divisible by \(250\): the last three digits are divisible by \(250\).
For example, \(43\,572\) is divisible by \(6\) because it is even and
\[ 4+3+5+7+2=21, \]
which is divisible by \(3\).
For primality, check divisibility by prime numbers up to the square root of the number. For instance, \(127\) is not divisible by \(2,3,5,7\), or \(11\), so it is prime.
Обсуждение
7 сообщений А
In short
a Yes, b Yes, c Yes, d Yes, e Yes, f No, g No, h Yes, i Yes, j Yes.
67, 97, 127
301 — Yes; 408 — No; 18088 — Yes
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Write 5 sentences about school clean lines share care about dropping litters with easy words
We should keep our school clean.
We must not drop litter on the floor.
We should put rubbish in the bin.
We can help clean our classroom.
A clean school is nice for everyone.
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Can you change 5
- A clean school makes us happy.
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Answers in short
