2.3 Calculate saach of the tollowing without using a calculator: \( 378539+46285 \) \( \qquad \) \( \qquad \) \( \qquad \) \( \qquad \) 2.3.2 \( 623341-236768 \) \( \qquad \) \( \qquad \) \( \qquad \) \begin{tabular}{l|l} & \\ 2.3 .3 & \( 315 \times 236 \) \end{tabular} \( \qquad \)

To add \( 378539 + 46285 \), let's stack the numbers and add them column by column. Start from the right: 9 + 5 = 14 (write 4, carry 1) 3 + 8 + 1 = 12 (write 2, carry 1) 5 + 2 + 1 = 8 8 + 4 = 12 (write 2, carry 1) 3 + 6 + 1 = 10 (write 0, carry 1) 4 + 1 = 5 So, \( 378539 + 46285 = 424824 \). For the subtraction \( 623341 - 236768 \), align the numbers downwards starting from the right: 1. 1 cannot subtract 8, so borrow 1 from 4, making it 11. Then it becomes 11 - 8 = 3. 2. Now, 3 becomes 2. 2 cannot subtract 6; borrow from 3 (making it 2), transforming 2 to 12, giving 12 - 6 = 6. 3. Move on: 2 - 7 (borrow one from 3), making it 12 - 7 = 5. 4. Proceed next: 3 - 3 = 0. 5. Finally, 6 - 2 = 4. So, \( 623341 - 236768 = 386573 \). For the multiplication \( 315 \times 236 \), a neat trick is to break it down: First, calculate \( 315 \times 200 = 63000 \). Then \( 315 \times 30 = 9450 \). Finally, \( 315 \times 6 = 1890 \). Now, simply add them together: 63000 + 9450 + 1890 = 75340. Thus, \( 315 \times 236 = 74340 \).