955, 536. Calculating machines; checking entries. ING. C. OLIVETTI & CO. S.p.A. Aug. 29, 1962 [Aug. 31, 1961], No. 33133/62. Heading G4B. To check an account number the transfer mechanism of the accumulator holding the number is disabled and the tens complement of the significant digits of the number is entered additively. In a further machine cycle the accumulator is checked that it is clear. Preferably the functions are carriage controlled using stops of the kind described in Specification 773,004 and the transfer mechanism is that described in Specification 768,395 in which transfer is effected by rocking toothed levers 36 by means of a bail 38 when the accumulator 6 is brought into engagement with the levers. Inhibiting transfer. A control slide 56 has a projection 77 which when the slide is moved forwards to start a cycle moves link 68 rearwardly through lever 73. Movement of main shaft 10 releases bellcrank 62 which releases bellcrank 57 to spring 59 for anti-clockwise movement. End 53 engages lug 52 on bail 38 preventing the transfer effecting movement. Sensing zero position of actuator. If an actuator 5 (Fig. 2) is moved from zero position a latch 22 stated to control zero printing is released to engage a bail 26 on a yoke 27. In this case a cam operated lever 31 cannot rock the yoke 27 and its extension 35 and release of lever 101 to its spring is prevented (Fig. 1). Checking operation. The account number is entered when the machine is positioned against the appropriate control stop. The check number is entered on the next cycle after the machine has tabulated to a control slide having a projection 77 so that transfer is inhibited. Finally, a total-taking cycle is initiated. A slide 50 is moved rearwardly rocking lever 93 anticlockwise and lowering a slide 81 so that projection 98 is out of register with lug 99 on lever 101. If the total registered by the actuators is zero yoke 27 will not be latched by any member 22 and lever 101 is freed to rock so that lug 99 is opposite projection 98. If any of the actuators do not register zero lug 99 will remain in the position shown. Slide 81 is then free to move forward when pin 86 on cam 51 disengages bellcrank 83. A pawl 89 then moves downward to signal an error by any means. A check is also made that the actuators are registering non-zero amounts on the additive entries. Lever 101 is rocked if all the actuators register zero and slide 81 is free to move forward (slide 50 is not operated in additive cycles) and pawl 89 indicates an error. Such a check requires a projection 77 on all the control slides so that bellcrank 57 can release slide 81 for possible forward movement.