What is the value of 7 + 5 × 3 − 4?
- 32
- 18 Correct answer.
- 22
- 28
Explanation
Order of operations requires multiplication before addition and subtraction, so 5 × 3 = 15 first. Then 7 + 15 − 4 = 18, working left to right for the remaining operations.
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Order of operations requires multiplication before addition and subtraction, so 5 × 3 = 15 first. Then 7 + 15 − 4 = 18, working left to right for the remaining operations.
A prime has exactly two positive factors, 1 and itself. The number 29 has no factors other than 1 and 29, so it is prime.
The greatest common divisor is the largest number dividing both values evenly. Factorising gives 36 = 2² × 3² and 60 = 2² × 3 × 5, so the shared product is 2² × 3 = 12.
To convert a terminating decimal to a fraction, place the digits over the appropriate power of ten and simplify. Here 375/1000 reduces by dividing numerator and denominator by 125 to give 3/8.
Adding two negatives gives −13, and subtracting a negative is equivalent to adding its positive. So −13 + 3 = −10.
When multiplying powers with the same base, add the exponents. Thus 2³ × 2⁴ = 2^(3+4) = 2⁷.
Compare decimals by their place values: 0.006 is six thousandths, 0.06 is six hundredths, and 0.6 is six tenths. Comparing place values gives the ascending order 0.006, 0.06, 0.6.
A square root asks which number multiplied by itself gives the value. Since 12 × 12 = 144, the square root of 144 is 12.
Dividing by a fraction is the same as multiplying by its reciprocal. So 3/4 × 5/2 = 15/8, which cannot be simplified further.
An increase of 25% multiplies the price by 1.25, giving $100. A subsequent 20% reduction multiplies by 0.8, so $100 × 0.8 = $80, returning to the original price.
The lowest common multiple is the smallest number divisible by both values. Multiples of 12 are 12, 24, 36..., and 24 is the first that is also a multiple of 8, so the answer is 24.
Scientific notation writes a number as a coefficient between 1 and 10 multiplied by a power of ten. Moving the decimal point four places right gives 4.5, so the exponent is −4.
Multiply the coefficients and add the exponents of like bases. Here 2 × 3 = 6 and x³ × x⁴ = x^(3+4) = x⁷, giving 6x⁷.
Set up the proportion sugar/flour = 2/5. With 350 g of flour, sugar = (2/5) × 350 = 140 g.
Absolute value gives the distance from zero, so |−7| = 7 and |3 − 9| = |−6| = 6. Their sum is 7 + 6 = 13.
An irrational number cannot be written as a fraction of integers and has a non-terminating, non-repeating decimal. The square root of 2 is such a number, so it is irrational.
Any nonzero number raised to the power 0 equals 1, and any number to the power 1 is itself. Thus 5⁰ + 5¹ = 1 + 5 = 6.
An increase of 40% means the new value is 1.4 times the original. Dividing 84 by 1.4 gives 60, so the original number was 60.
Multiply the digits: 6 × 4 = 24. The factors have one and one decimal place respectively, so the product needs two decimal places, giving 0.24.
The factorial n! is the product of all positive integers up to n. So 4! = 24 and 3! = 6, and 24 ÷ 6 = 4, which also follows from cancelling 3! in 4 × 3!/3!.
A negative exponent indicates the reciprocal of the corresponding positive power. Thus 2⁻³ = 1/2³ = 1/8.
The largest share corresponds to 5 parts, so each part is 60 ÷ 5 = $12. The total is 3 + 4 + 5 = 12 parts, giving 12 × 12 = $144.
A negative exponent takes the reciprocal of the base before applying the positive power. The reciprocal of 2/3 is 3/2, and (3/2)² = 9/4.
Successive discounts multiply: the final price is 0.85 × 0.90 = 0.765 of the original. Dividing 61.20 by 0.765 gives $80.
The lowest common multiple of 1 through 10 is the smallest number divisible by each of them. Taking the highest power of each prime present (2³ × 3² × 5 × 7) gives 2520, so it is divisible by every integer from 1 to 10.
Subtracting a negative number is the same as adding its positive value, so 7 − (−4) = 7 + 4 = 11.
A prime has exactly two factors, 1 and itself; 29 has no factor other than 1 and 29. The other numbers are all divisible by 3.
Writing 36 = 2² × 3² and 48 = 2⁴ × 3, the HCF takes the lowest power of each shared prime: 2² × 3 = 12.
0.25 means 25 hundredths, so 0.25 = 25/100. Dividing numerator and denominator by 25 gives 1/4.
Evaluate powers before adding: 3² = 9 and 2³ = 8, so the sum is 9 + 8 = 17.
A common multiple must be divisible by both 6 and 9; 54 = 6 × 9 and 54 = 9 × 6. The lowest common multiple of 6 and 9 is 18, and 54 is a multiple of 18.
Rewrite 2/3 as 4/6 so both fractions share the denominator 6, then add: 4/6 + 1/6 = 5/6.
Multiply both numbers by 100 to remove the decimal from the divisor: 4.8 ÷ 0.06 = 480 ÷ 6 = 80.
To convert a fraction to a percentage, multiply by 100: (2/5) × 100 = 40. So 2/5 equals 40%.
A negative number squared is positive, so (−3)² = 9; a negative number cubed stays negative, so (−2)³ = −8. Then 9 − (−8) = 9 + 8 = 17.
A multiplier of 1 + r represents an increase of r expressed as a decimal. Since 1.08 = 1 + 0.08, the quantity rises by 0.08, which is 8%.
Multiply numerators and denominators: (3 × 8)/(4 × 9) = 24/36. Dividing both parts by 12 gives the simplest form 2/3.
When multiplying powers with the same base, add the exponents: 5⁻² × 5⁴ = 5^(−2+4) = 5² = 25.
The average speed is 240 ÷ 3 = 80 km/h. In 5 hours the car covers 80 × 5 = 400 km.
Since 0.7 × 0.7 = 0.49, the square root of 0.49 is 0.7. The number of decimal places in the square is double that of its root.
A number is divisible by 9 exactly when its digit sum is divisible by 9. For 4725 the digits sum to 4 + 7 + 2 + 5 = 18, and 18 is divisible by 9.
The tax is 8% of $45, which is 0.08 × 45 = $3.60. Adding this to the original price gives $45 + $3.60 = $48.60.
Compute each power: (1/2)³ = 1/8 and (1/2)² = 1/4 = 2/8. Adding gives 1/8 + 2/8 = 3/8.
For a prime factorisation with exponents a, b, c, the number of divisors is (a+1)(b+1)(c+1). Here that gives (3+1)(2+1)(1+1) = 4 × 3 × 2 = 24.
A 20% reduction uses the multiplier 0.8, and a 25% increase uses 1.25. Their product is 0.8 × 1.25 = 1, so the final price equals the original price.
Scientific notation writes a number as a × 10ⁿ with 1 ≤ a < 10. Moving the decimal point in 0.00036 four places right gives 3.6, so the exponent is −4.
Each trailing zero comes from a factor of 10 = 2 × 5. The number of complete pairs of 2s and 5s is limited by the smaller exponent, min(5, 3) = 3, so N ends in 3 zeros.
If the product were rational, dividing by the non-zero rational factor would make the irrational factor rational, a contradiction. So the product must be irrational.
Write each number in prime factor form: 84 = 2² × 3 × 7 and 120 = 2³ × 3 × 5. The GCD takes the lowest power of each shared prime, giving 2² × 3 = 12.
A decrease of 15% leaves 85% of the original, so 0.85x = 102. Dividing both sides by 0.85 gives x = 120.