Number Play

Farah compares two numbers, 4,809 and 4,890, and says 4,809 is bigger because it ends in 9, and 9 is the biggest single digit. Her brother says you have to compare digit by digit starting from the left, not just look for a big digit anywhere. Who is right?

Ravi wants to add 48 and 37 quickly. He rounds 48 up to 50 and 37 up to 40, adds those to get 90, and writes that down as the exact total. Sunita says his answer is only close, not exact. Who is right?

Karan looks at the sequence 1, 4, 9, 16 and notices each number is 3 more than the last near the start, so he guesses the next number is 19. Diya says you cannot be sure the pattern stays "add 3" without checking more carefully. Who is right?

Rohan says adding two 3-digit numbers always gives a 3-digit answer. His sister says that is not always true. Who is right?

Someone asks whether 84 is in the count-by-6s list: 6, 12, 18, 24 and so on. Naveen says yes, because 84 is an even number and 6 is also even. Ira says being even is not enough by itself — you have to actually check if it divides evenly. Who is right, and is Naveen's reason solid?

Tanya wants to estimate 61 + 68. She rounds both DOWN to 60 and adds: 60 + 60 = 120. But the real answer is 129. Her friend says rounding each to the NEAREST ten gives a better estimate. Who is right?