# IGCSE Mathematics Paper-1: Specimen Questions with Answers 276 - 281 of 324

## Question 276

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### Write in Short

From the list above, write down

A prime number,

### Explanation

• A prime number is a whole number greater than 1 whose only factors are 1 and itself.
• In this number is prime number
• Because
• And 2 is a prime number.

## Question 277

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### Write in Short

Expand and simplify

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Simplify

Here given the

## Question 279

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### Write in Short

Look at the sequence of diagrams above.

The number of dots in each diagram is given in the table below.

Find the number of dots in

Diagram 50,

### Explanation

For this sequence the diffrence between each diagram and next diagram is 3.

Here

Here apply this equaion

The number of dots in 50th diagram is 160.

## Question 280

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### Write in Short

Calculate the perimeter of the shape.

### Explanation

• The perimeter is Where r is the radius and d is the diameter Here it is a semicircles, that is half the circle is the perimeter Here

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