I tried it on gpt-4-turbo and it seems to give the right answer:

>Let's calculate:494,547,645,908,151+7,640,745,309,351,279,642=7,641,239,856,997,187,793 >494,547,645,908,151+7,640,745,309,351,279,642=7,641,239,856,997,187,793 >Answer: 7,641,239,856,997,187,793