If MUMBAI is coded as 202108, DELHI will be coded as ________ ?

Concept: In this alphabet-to-number coding scheme, every letter of a word is replaced by a single digit: take the letter's position in the English alphabet (A = 1, B = 2, ..., Z = 26), subtract 1 from that position, and keep only the unit (last) digit of the result. Writing these digits in the same left-to-right order as the letters gives the code for the whole word.

Applying it to MUMBAI (checking the given code):

Reading these digits in order — M, U, M, B, A, I — gives 2, 0, 2, 1, 0, 8, i.e. 202108, exactly the code given for MUMBAI. This confirms the rule.

Applying the same rule to DELHI:

Reading these digits in order — D, E, L, H, I — gives 3, 4, 1, 7, 8, so DELHI is coded as 34178.

Cross-check: Counting each letter's position from the other end of the alphabet (Z = 1st-from-the-end, Y = 2nd, ..., A = 26th) and converting back with position-from-A = 27 − position-from-Z independently gives D = 27−23 = 4, E = 27−22 = 5, L = 27−15 = 12, H = 27−19 = 8, I = 27−18 = 9 — the same positions used above, now re-derived by a separate counting method. Re-applying the rule to these confirms the code 34178.