The Number Sense Showdown.

Who discovered zero (0)?

• Brahmagupta

• Euclid

• Pythagoras

• Archimedes

Answer explanation

Brahmagupta, an Indian mathematician, was the first to formalize the concept of zero (0) in the 7th century. He defined it as a number and established rules for its use in calculations, making him the key figure in its discovery.

What is the next number in the sequence: 1, 3, 6, 10, 15, 21, _____?

• 30

• 25

• 28

• 35

Answer explanation

The sequence consists of triangular numbers: 1 (1), 3 (1+2), 6 (1+2+3), 10 (1+2+3+4), 15 (1+2+3+4+5), 21 (1+2+3+4+5+6). The next number is 28 (1+2+3+4+5+6+7), making 28 the correct answer.

I have 6 eggs. I broke two, fried two, and ate two. How many eggs are left?

• 0

• 4

• 6

• 2

Answer explanation

You started with 6 eggs. Breaking, frying, and eating two eggs does not change the total count of eggs left. Therefore, 6 - 2 = 4 eggs remain.

Which prime number is closest to 100?

• 89

• 103

• 97

• 101

Answer explanation

The prime numbers closest to 100 are 97, 101, and 103. Among these, 101 is the closest to 100, being only 1 unit away, while 97 is 3 units away and 103 is 3 units away as well.

I am a 3-digit number. The second digit is 4 times bigger than the third digit. The first digit is 3 less than the second digit. What is the number?

• 341

• 241

• 141

• 144

Answer explanation

Let the third digit be x. Then the second digit is 4x, and the first digit is 4x - 3. The only valid digits are 0-9. Setting x=1 gives 4x=4 and 4x-3=1, forming the number 141, which satisfies all conditions.

You cut a cake into four equal pieces. If you eat 3 pieces, what fraction of the cake is left?

• 3/4

• 1/2

• 1/3

• 1/4

Answer explanation

You cut the cake into 4 equal pieces. If you eat 3 pieces, you have 1 piece left. The fraction of the cake remaining is 1 out of 4, which is 1/4.

The product of 121 x 0 x 200 x 25 is?

• 1000

• 0

• 5000

• 6050

Answer explanation

The product of any number and 0 is always 0. Since 121 x 0 x 200 x 25 includes a multiplication by 0, the entire product is 0.

How can you obtain the number 100 by using four sevens (7's) and one (1)?

Answer explanation

You can obtain 100 by using the equation (7 + 7 + 7) * (7 - 1). This simplifies to 21 * 6, which equals 126. However, to get exactly 100, you can use 177 - 77 = 100, where 177 is formed by 7, 7, 7, and 1.

Which three numbers have the same answer whether they are added or multiplied together?

• 1, 2, 3

• 2, 4, 6

• 1, 1, 1

• 3, 3, 3

Answer explanation

The numbers 1, 2, and 3 satisfy the condition because 1 + 2 + 3 = 6 and 1 × 2 × 3 = 6. Thus, they yield the same result when added or multiplied, making this the correct choice.

Which number is NOT a multiple of 9?

• 108

• 117

• 124

• 135

Answer explanation

To determine which number is not a multiple of 9, we check each option. 108, 117, and 135 are multiples of 9, while 124 is not, as it does not divide evenly by 9.