Count forwards and backwards in steps of power of 10 - Reasoning

The National Curriculum objective for this activity is to develop the ability of students to count forwards and backwards in steps of powers of 10, up to one million. This is a fundamental aspect of understanding number and place value for Year 5 students. The task involves reasoning skills to determine who has made an error in their counting sequence. Malachi claims to be counting in hundreds from 723 and believes he will include 1,230 in his sequence. However, upon closer examination, it is clear that Malachi has made a mistake. When counting in increments of 100 from 723, he would reach numbers like 823, 923, 1,023, 1,123, and so on, but not 1,230. Instead, he would include 1,223 as part of the sequence.

Other students, Tia and Rosie, also present their counting sequences. Tia is counting in tens from 56 and expects to include 126 in her sequence, which is correct since 126 is indeed a part of that sequence (66, 76, 86, 96, 106, 116, 126). Rosie is counting in tens of thousands from 1,800 and anticipates that she will include 41,800, which is also correct, as the sequence would include 11,800, 21,800, 31,800, and finally 41,800. Therefore, among the three students, Malachi is the one who has made a mistake in his counting sequence, as his expected number does not align with the pattern of counting in hundreds.