Write the following in Hindu-Arabic numerals:
XXIX

Hint: In this question it is given that we have to write ‘XXIX’ in Hindu-Arabic numerals. So for this we need to know that the symbol X = 10 and I = 1 also we need to know some rules to transform Roman numerals to Hindu-Arabic numerals, so the rules are:
1. If a smaller symbol is written to the right of a symbol with greater value, then its value gets added to the value of the greater symbol. For example, XI=10 +1= 11
2. If a smaller symbol is written on the left of a symbol with greater value, then its value is subtracted from the value of the greater symbol. IV= 5-1=4, IX =10-1 = 9 etc.

Complete step-by-step answer:
Here the given Roman numeral is XXIX
So by the above rules we can say that, initially X is repeated once so we have to add them i.e XX= 10+10 = 20, (by rule number 3)
Now as we know that IX = 10-1 =9 (by rule number 2)
Now in XXIX, IX is written to the right side of XX so we have to add them, so by rule (1) we can write,
XXIV = 20+9 = 29.

Note: While putting the values of Roman symbols, you need to know that if a symbol is repeated then its value is added as many times as it occurs. For example, II=2, XX=20 etc. but the restriction is, you cannot repeat a symbol more than three times.