Keep the step and the position separate.
Practise signed differences, missing middle terms and position counting. Six original answers are a local revision record, without a speed or ability band.
The six questions each contribute one correct answer. The count describes this fixed rule family and edition, without a speed adjustment, IQ conversion or comparison with other people. Every worked answer and this complete guide is available at every count.
The question supplies a rule family
These six questions explicitly require one constant additive step. Your task is to infer that step from the visible terms and apply it at the missing position. This condition matters: a finite list of numbers can be extended by many formulas when no family is specified. Here the stated family makes the exercise testable. A correct choice means that option fits the condition and all the displayed terms; it does not mean you have discovered the only mathematically imaginable continuation.
A fresh signed-step example
Consider 23, 14, 5, −4, ?. The consecutive differences are −9, −9 and −9, so the next value is −13. Write the subtraction in the same order each time: later term minus earlier term. Reversing that order changes the sign and suggests growth instead of decline. Crossing zero requires no new rule. If you see a positive answer among the alternatives, check whether it came from taking an absolute distance and forgetting the direction.
A blank in the middle has two checks
For −15, −7, ?, 9, 17, the fixed step is +8. The blank must be 1 because −7 + 8 = 1 and 1 + 8 = 9. Checking only one side can let a mistaken step survive. When the blank separates two visible terms, the difference between those visible terms spans two steps, not one. Here 9 − (−7) = 16, which must be divided by two to recover the step of 8.
Count transitions rather than terms
If a first term is 6 and every step adds 4, the eighth term is 6 + 7 × 4 = 34. There are seven transitions between positions one and eight. Adding eight steps would produce the ninth term instead. Marking positions underneath a row helps when a question displays more terms than expected or asks for an interior term. The same indexing principle applies to descending sequences; a negative step changes the calculation, not the number of transitions.
Check the whole visible row
One adjacent pair identifies a possible step, but every other pair must agree with it. For 10, 16, 22, 29, the first two gaps are 6 while the last is 7, so the row does not meet a constant-step condition as written. Do not repair a given number silently to preserve a preferred rule. In this practice bank the checked answer fits the displayed values exactly, with no tolerance or rounding convention needed for the constant-difference items.
Separate sign, indexing and arithmetic slips
After a missed question, write the step you used, the target position and one calculation from each side of the blank when possible. This distinguishes a wrong sign from an off-by-one position or an arithmetic slip. Try a fresh row using a different first term but the same step, then explain why the method still works. Merely selecting the remembered letter on a second attempt does not show that you can reconstruct the relationship independently.
Read the count narrowly
A count out of six is a record of these particular fixed-step questions. It has no established percentile, hiring threshold, speed meaning or intelligence interpretation. Paper and a calculator are permitted, and there is no countdown. Someone who misreads one minus sign may lose an item without lacking the underlying concept. Use the full rationales to locate the error, then move to ratio or changing-gap questions only when you want a different rule family rather than a higher ability label.