In this context, where it implies analyzing or considering something carefully, a more suitable translation would be "一项有趣的分析", which literally means "an interesting analysis." This translation better captures the essence of reviewing and evaluating the performance of the BRICS nations over the last decade.

However, I suggest not translating "exercise" here as "But looking at the performance of the four original members - Brazil, Russia, India, China - over the last decade is interesting" is more idiomatic for Chinese translation.