Correct Answer: +, ×, –, ÷, =

Solution : Given:
45 * 86 * 23 * 36 * 18 * 2021

Replace the * sign given in the equation with the assigned signs in the options.
Let's check the options –
First option: ×, +, –, ÷, =
⇒ 45 × 86 + 23 – 36 ÷ 18 = 2021
= 45 × 86 + 23 – 2
= 3870 + 23 – 2
= 3893 – 2
= 3891 ≠ 2021
Second option: +, –, ×, ÷, =
⇒ 45 + 86 – 23 × 36 ÷ 18 = 2021
= 45 + 86 – 23 × 2
= 45 + 86 – 46
= 131 – 46
= 85 ≠ 2021
Third option: –, ×, +, ÷, =
⇒ 45 – 86 × 23 + 36 ÷ 18 = 2021
= 45 – 86 × 23 + 2
= 45 – 1978 + 2
= 47 – 1978
= –1931 ≠ 2021
Fourth option: +, ×, –, ÷, =
⇒ 45 + 86 × 23 – 36 ÷ 18 = 2021
= 45 + 86 × 23 – 2
= 45 + 1978 – 2
= 2023 – 2
= 2021 = R.H.S.

So, only the fourth option satisfies the given equation. Hence, the fourth option is correct.